Combined Application of Prototype Ultrasound and BSA-Loaded PLGA Particles for Protein Delivery.

PURPOSE: To develop an in vitro culture system for tissue engineering to mimic the in vivo environment and evaluate the applicability of ultrasound and PLGA particle system. METHODS: For tissue engineering, large molecules such as growth factors for cell differentiation should be supplied in a controlled manner into the culture system, and the in vivo microenvironment need to be reproduced in the system for the regulation of cellular function. In this study, portable prototype ultrasound with low intensity was devised and tested for protein release from bovine serum albumin (BSA)-loaded poly(lactic-co-glycolic acid) (PLGA) particles. RESULTS: BSA-loaded PLGA particles were prepared using various types of PLGA reagents and their physicochemical properties were characterized including particle size, shape, or aqueous wetting profiles. The BSA-loaded formulation showed nano-ranged size distribution with optimal physical stability during storage period, and protein release behaviors in a controlled manner. Notably, the application of prototype ultrasound with low intensity influenced protein release patterns in the culture system containing the BSA-loaded PLGA formulation. The results revealed that the portable ultrasound set controlled by the computer could contribute for the protein delivery in the culture medium. CONCLUSIONS: This study suggests that combined application with ultrasound and protein-loaded PLGA encapsulation system could be utilized to improve culture system for tissue engineering or cell regeneration therapy.

Preparation and Characterization of Tenofovir Disoproxil-Loaded Enteric Microparticle.

Tenofovir disoproxil (TD) has narrow absorption site mostly in upper intestinal tract where tenofovir rapidly decomposes. The aim of this work was to prepare and evaluate tenofovir disoproxil-loaded enteric microparticles (TDEMs) for the enhanced duodenal delivery. TDEMs were composed of TD, eudragit L-100 (EL) and ethyl cellulose (EC) as release-controlling polymers. For the physicochemical characterization, TDEMs were evaluated in terms of encapsulation efficiency (EE%), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR). The dissolution test was also performed while continuously changing the medium pH. The EE% of TD in TDEMs was good and more than 90%. The EC and EL formed a physically mixed structure and maintained their respective properties in TDEMs as confirmed by SEM image and FT-IR analysis. Combination of EL and EC gave higher enteric properties to TDEMs than the single use of EL or EC. The optimized TDEM (TD/EL/EC = 0.2/1/1, w/w/w ratio) yielded mean dissolution rate less than 10% in 1 h at pH 1.2, but completed dissolution with a dissolution more than 85% within 1 h at pH 6.5. Thus, the suggested TDEM would be promising enteric microparticles for the intensive delivery of TD to the duodenum.